Wi-Fi Direct APIs允许应用连接周围的设备，而不用通过网络或者热点，点对点直接连接。应用可以快速的发现周围设备并与之交互，而有效作用距离大于蓝牙。这篇博客对如何实现Wi-Fi P2P设备间的连接做一个总结，如有不对之处，欢迎拍砖。
打开应用后，应用程序开始查找附近的可连接设备，并把结果显示在一个NumberPicker中，我们可以选择一个设备，然后点击CONNECT按钮，就可以连接到附近的设备。
Wi-Fi P2P连接过程总结
1.权限
首先我们需要这三个权限。
<uses-permission
android:required="true"
android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.INTERNET"/>
2.注册广播接收器
我们需要如下四个广播：
WIFI_P2P_STATE_CHANGED_ACTION
Indicates whether Wi-Fi P2P is enabled
—- 表明Wi-Fi P2P有没有使能
WIFI_P2P_PEERS_CHANGED_ACTION
Indicates that the available peer list has changed.
—- 表明可用的peer list发生了改变
WIFI_P2P_CONNECTION_CHANGED_ACTION
Indicates the state of Wi-Fi P2P connectivity has changed.
—- 表明Wi-Fi P2P连接状态发生了改变
WIFI_P2P_THIS_DEVICE_CHANGED_ACTION
Indicates this device’s configuration details have changed.
—-表明这个设备的配置信息发生了改变
3.初始化
mManager = (WifiP2pManager)getSystemService(Context.WIFI_P2P_SERVICE);
mChannel = mManager.initialize(this,getMainLooper(), null);
initialize方法返回一个WifiP2pManager.Channel的实例，标示一个 通道，以后我们就要使用这个通道来查找和连接Wi-Fi P2P设备。
4.开始查找附近设备
mManager.discoverPeers(mChannel, newWifiP2pManager.ActionListener() {
@Override
public void **uccess() {
Log.d(TAG,"**uccess");
}
@Override
public void onFailure(int reasonCode) {
Log.d(TAG,"onFailure");
}
});
discoverPeers方法发起查找，这个查找是异步的，查找结束后回调方法会被调用，从而使我们可以得知查找成功还是失败。
5.获取设备列表
discoverPeers发起查找以后，一旦查找到附近设备，WIFI_P2P_PEERS_CHANGED_ACTION广播就会触发，我们可以在该广播中调用requestPeers方法来请求过去设备列表。
requestPeers需要两个参数，第一个就是我们的通道，由mManager.initialize方法返回，第二个参数是一个**器。发送获取设备列表请求后，**器中的方法onPeersAvailable就会被调用，我们可以在其中获取到附近的设备。
下面为请求获取设备列表的代码：
if (mManager != null) {
mManager.requestPeers(mChannel,peerListListener);
}
下面为**器中获取附近设备的代码：
private PeerListListener peerListListener =new PeerListListener(){
@Override
public voidonPeersAvailable(WifiP2pDeviceList peerList) {
// Out with the old, in with the new.
peers.clear();
peers.addAll(peerList.getDeviceList());
// If an AdapterView is backed by this data, notify it
// of the change. For instance, if you have a ListView of available
// peers, trigger an update.
((WiFiPeerListAdapter)getListAdapter()).notifyDataSetChanged();
if (peers.size() == 0) {
Log.d(WiFiDirectActivity.TAG, "No devices found");
return;
}
}
}
6.连接到设备
@Override
public void connect() {
// Picking the first device found on thenetwork.
WifiP2pDevice device = peers.get(0);
WifiP2pConfig config = newWifiP2pConfig();
config.deviceAddress =device.deviceAddress;
config.wps.setup = WpsInfo.PBC;
mManager.connect(mChannel, config, newActionListener() {
@Override
public void **uccess() {
// WiFiDirectBroadcastReceiver will notifyus. Ignore for now.
}
@Override
public void onFailure(int reason) {
}
});
}
连接成功后，我们就会收到WIFI_P2P_CONNECTION_CHANGED_ACTION广播，我们可以在广播中请求过去更加详细的信息，使用的方法是：mManager.requestConnectionInfo(mChannel, connectionListener);
if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
if (mManager == null) {
return;
}
NetworkInfo networkInfo = (NetworkInfo) intent
.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);
if (networkInfo.isConnected()) {
// We are connected with the other device,request connection
// info to find group owner IP
mManager.requestConnectionInfo(mChannel,connectionListener);
}
requestConnectionInfo方法的第二个参数也是一个**器，请求过去详细信息以后，这个**器的onConnectionInfoAvailable方法就会被调用，我们可以在其中获取谁是“群主”等信息。
实例
以上为连接一个Wi-Fi P2P设备的步骤，下面博客一开始展示的应用程序的代码，供大家参考：
MainActivity.java
packagecom.jinwei.wifip2ptest;
import android.app.Activity;
importandroid.content.BroadcastReceiver;
importandroid.content.Context;
importandroid.content.Intent;
importandroid.content.IntentFilter;
importandroid.net.NetworkInfo;
importandroid.net.wifi.WpsInfo;
importandroid.net.wifi.p2p.WifiP2pConfig;
importandroid.net.wifi.p2p.WifiP2pDevice;
importandroid.net.wifi.p2p.WifiP2pDeviceList;
importandroid.net.wifi.p2p.WifiP2pInfo;
importandroid.net.wifi.p2p.WifiP2pManager;
importandroid.support.v7.app.AppCompatActivity;
import android.os.Bundle;
importandroid.util.Log;
importandroid.view.View;
importandroid.view.ViewGroup;
importandroid.widget.Button;
importandroid.widget.LinearLayout;
importandroid.widget.NumberPicker;
importandroid.widget.TextView;
import android.widget.Toast;
importjava.net.InetAddress;
importjava.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity implements WifiP2pManager.PeerListListener,WifiP2pManager.ConnectionInfoListener{
private final IntentFilterintentFilter = new IntentFilter();
WifiP2pManager.Channel mChannel;
WifiP2pManager mManager;
NumberPicker picker;
Button button;
TextView textView;
private final String TAG = "MainActivity";
private final BroadcastReceivermReceiver = newBroadcastReceiver() {
@Override
public void onReceive(Contextcontext, Intent intent) {
String action = intent.getAction();
if(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
Log.d(TAG,"WIFI_P2P_STATE_CHANGED_ACTION");
} else if(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
Log.d(TAG,"WIFI_P2P_PEERS_CHANGED_ACTION");
if (mManager != null) {
mManager.requestPeers(mChannel,MainActivity.this);
}
Log.d(TAG, "P2P peers changed");
} else if(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
Log.d(TAG,"WIFI_P2P_CONNECTION_CHANGED_ACTION");
if (mManager == null) {
return;
}
NetworkInfo networkInfo =(NetworkInfo) intent
.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);
if (networkInfo.isConnected()) {
mManager.requestConnectionInfo(mChannel, MainActivity.this);
}
} else if(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
Log.d(TAG,"WIFI_P2P_THIS_DEVICE_CHANGED_ACTION");
}
}
};
@Override
protected void onCreate(BundlesavedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
mManager = (WifiP2pManager)getSystemService(Context.WIFI_P2P_SERVICE);
mChannel = mManager.initialize(this,getMainLooper(), null);
picker = (NumberPicker)findViewById(R.id.pick);
picker.setDescendantFocusability(NumberPicker.FOCUS_BLOCK_DESCENDANTS);
peersName = new String[1];
peersName[0]="No Devices";
picker.setDisplayedValues(peersName);
button = (Button)findViewById(R.id.button);
button.setOnClickListener(newView.OnClickListener() {
@Override
public void onClick(View v) {
int num =picker.getValue();
connect(num);
}
});
textView = (TextView)findViewById(R.id.text);
}
@Override
protected void onResume() {
super.onResume();
registerReceiver(mReceiver,intentFilter);
mManager.discoverPeers(mChannel, newWifiP2pManager.ActionListener() {
@Override
public void **uccess() {
Log.d(TAG,"**uccess");
}
@Override
public void onFailure(int reasonCode) {
Log.d(TAG,"onFailure");
}
});
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(mReceiver);
}
private List<WifiP2pDevice> peers = newArrayList<>();
private String[] peersName;
@Override
public void onPeersAvailable(WifiP2pDeviceListpeerList) {
peers.clear();
peers.addAll(peerList.getDeviceList());
if (peers.size() == 0) {
Log.d(TAG, "No devices found");
textView.setVisibility(View.INVISIBLE);
if (peersName.length>0){
peersName[0]="No Devices";
}else {
peersName = new String[1];
peersName[0]="No Devices";
}
return;
}else{
peersName = newString[peers.size()];
int i=0;
for(WifiP2pDevicedevice: peers){
peersName[i++]=device.deviceName;
}
textView.setVisibility(View.VISIBLE);
textView.setText("(avaliable)");
}
picker.setDisplayedValues(peersName);
}
public void connect(final int num) {
// Picking the first device found on thenetwork.
WifiP2pDevice device = peers.get(num);
WifiP2pConfig config = newWifiP2pConfig();
config.deviceAddress = device.deviceAddress;
config.wps.setup = WpsInfo.PBC;
mManager.connect(mChannel, config, newWifiP2pManager.ActionListener() {
@Override
public void **uccess() {
Log.d(TAG,"connect sucess");
}
@Override
public void onFailure(int reason) {
Log.d(TAG,"connect fail");
}
});
}
@Override
public void onConnectionInfoAvailable(WifiP2pInfoinfo) {
textView.setVisibility(View.VISIBLE);
textView.setText("(connected)");
// InetAddress from WifiP2pInfo struct.
InetAddress groupOwnerAddress =info.groupOwnerAddress;
Log.d(TAG,"onConnectionInfoAvailable");
Log.d(TAG,info.toString());
if (info.groupFormed &&info.isGroupOwner) {
} else if(info.groupFormed) {
}
}
}
布局文件activity_main.xml
<?xml version="1.0"encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.jinwei.wifip2ptest.MainActivity">
<TextView
android:text="Wi-Fi Direct Scaning..."
android:layout_centerHorizontal="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<NumberPicker
android:layout_centerInParent="true"
android:id="@+id/pick"
android:focusableInTouchMode="true"
android:focusable="true"
android:layout_width="200dp"
android:layout_height="200dp">
</NumberPicker>
<TextView
android:text="helllo"
android:layout_toRightOf="@+id/pick"
android:id="@+id/text"
android:visibility="invisible"
android:layout_centerVertical="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<Button
android:id="@+id/button"
android:text="connect"
android:background="@drawable/button_bg"
android:layout_below="@+id/pick"
android:layout_marginStart="700dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</RelativeLayout>
按钮的背景文件button_bg.xml
<?xml version="1.0"encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android" >
<item android:state_focused="true">
<shape android:shape="rectangle">
<corners android:bottomLeftRadius="5dip"
android:bottomRightRadius="5dip"
android:topLeftRadius="5dip"
android:topRightRadius="5dip" />
<solid android:color="@color/button_focus"/>
</shape>
</item>
<item android:state_focused="false">
<shape android:shape="rectangle">
<corners android:bottomLeftRadius="5dip"
android:bottomRightRadius="5dip"
android:topLeftRadius="5dip"
android:topRightRadius="5dip" />
<solid android:color="@color/button_color"/>
</shape>
</item>
<item android:state_selected="true">
<shape android:shape="rectangle">
<corners android:bottomLeftRadius="5dip"
android:bottomRightRadius="5dip"
android:topLeftRadius="5dip"
android:topRightRadius="5dip" />
<solid android:color="@color/button_focus"/>
</shape>
</item>
<item android:state_selected="false">
<shape android:shape="rectangle">
<corners android:bottomLeftRadius="5dip"
android:bottomRightRadius="5dip"
android:topLeftRadius="5dip"
android:topRightRadius="5dip" />
<solid android:color="@color/button_color"/>
</shape>
</item>
</selector>
AndroidManifest.xml文件
<?xml version="1.0"encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.jinwei.wifip2ptest">
<uses-permission
android:required="true"
android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.CHANGE_WIFI_STATE"/>
<uses-permission
android:required="true"
android:name="android.permission.INTERNET"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>19
Color.xml文件
<?xml version="1.0"encoding="utf-8"?>
<resources>
<color name="colorPrimary">#3F51B5</color>
<color name="colorPrimaryDark">#303F9F</color>
<color name="colorAccent">#FF4081</color>
<color name="button_color">#ff546f7a</color>
<color name="button_focus">#ff0277bd</color>
</resources>